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Old 01-16-2013, 11:29 AM   #324
_cy_ OP
Beastly Adventurer
 
Joined: Sep 2011
Location: Tulsa, Oklahoma
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Quote:
Originally Posted by Tweaker View Post
Unconfirmed reports say there was a battery warning in the cockpit and then a smell. The APU battery has no warning indicator so this points to the main battery in the forward section. This plane has been in service for one year to the day.

Yes, cy, fire is very serious, even more so than engine bits ripping into the cabin.. The 787 is being heavily scrutinized now, there was another fire in an A333 in Tokyo yesterday that nobody heard about and another emergency landing Monday of an USAirways flight for smoke in the cabin.

I imagine the charging circuitry will get a good scrutiny. Sourced from Thales, we can blame the French.
they need to yank out ALL lithium cobalt li-ion batteries out of 787!!! and replace with lithium iron phosphate or AGM. think in terms of cell volt multiples. 787 uses a 28V battery system. PB and LiFePO4 cells multiply up nicely and will both support 28V. (note Ni-cad and PB are already approved technologies which FAA has issued an emergency directive before)

LiFePO4 li-ion has about 1/2 energy density as lithium cobalt li-ion. so number of prismatic cells will be higher and larger than lithium cobalt to deliver same amp hour and volts.

charging requirements are different for LiFePO4, but rest of electronics should remain essentially the same.

Quote:
Originally Posted by RockyRaccoon View Post
I'm surprised they went with this technology, and even more surprised they didn't ask you before they did.
this is the most baffling part ... there is NO way those folks at GS Yusa and Thales didn't know dangers of lithium cobalt li-ion batteries. which are well known.

it's understandable why lithium cobalt was spec'd back in 2003 era ... but LOTS has happened since then. there is NO way the folks at GS Yusa and Thales didn't know about all the Sony laptops catching in fire and the massive number of battery replacement that followed. FAA restricting transport of li-ion cells catching on fire, etc.

the number of competent battery guys are small but they are out there. just so happens I've been involved with li-ion cells almost from the beginning when A123 had barely started.

strangely enough consumer use of li-ion cells happened on Candlepower forums. we among the world's first users of li-ion batteries in flashlights without protection circuits. lithium cobalt was the most commonly used li-ion cells. we went through all sorts of battery explosions back then. we were on the bleeding edge for consumer use of li-ion cells.

there's a little mostly unknown phenomena when lithium ions migrate during discharge and charging. if charging rates are too low for extend periods, dendrites may form very similar to metal forming like crystals during extended plating. if enough dendrites form and shorts out.... a fire could result. this is even with protection circuits working.

due to all the delays in 787 launch, an important question that comes into mind is how old are the batteries used in 787 and how were they stored? which really is a moot point as Lithium cobalt li-ion batteries should have never made it into production in 787.

_cy_ screwed with this post 01-22-2013 at 09:56 AM
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